Tuning mechanism for radio receiving set



Sept. v17. 1940. A. s. WELLS TUNING MECHANISM FOR RADIO RECHEIIZING SET Filed Apfil 25. 1938 hem: dzwzdpfza,

sqit. 17, 1940. 5, WELLS 2,214,785

mums lscxumlsm Fun mmo' RECEIVING 5151' Filed Ajaril 25. 1938 Shoots-Shoot 2 P 1940- A. s. WELLS TUNING MECHANISM FOR RADIO RECEIVING SET Filed April 25,- 1958 3 Sheets-Sheet 3 "III Patented Sept. 17, 1940 PATENT OFFICE.

some miommsm Foa namo nacmvwe saw Albert s. Wells, Chicago, 111., assignor to Wells- Gardner & ompany, Chicago, 111., a corpora- .tion of Illinois I Application April 25, 1938, Serial No. 204.021

50mins. (01374-10) It is a primary object of this invention-to provide a simple and efficient means for tuning a radio set into resonance with a desired station by operation of a selected manual. The mechanism employed for this purpose, as hereinafter disclosed, maybe quickly and readily pre-set for a number of selected stations, enabling the user to tune in with any one of said stations by operation of a single manual. The operating connections may include a series of driving manuals each movable toward and from an eccentrically rotatable shaft on which is mounted a plurality of cams or arms one of which is adapted to be driven by each manual through theexertion of 16 an operating force which proceeds with special mechanical advantage. all as hereinafter set forth. By the improvements which characterize this invention, the entire tuning mechanism can be assembled into aunit capable of quickand easy removal from or insertion into the radio chassis, and its several cams or arms may be pre-set or readjusted from time to time with a maximum of ease and certainty. Various other advantages in the directions of simplicity, econ- B omy and dependability are realized by the present mechanism which is fully described in the following specification and shown *'in the accompanying drawings in the manner following:

Figure 1 is a partial vertical section on line 0 l-i of Fig. 2, showingone 'ofthe manual-cam assemblies comprised in the'present mechanism; Fig. 2 is a vertical section through the tuning mechanism assembly, taken on line 2-2 of Fig. 1, one of the tuning levers beingshown as de- 35 pressed" while the others are in normally raised position; Figs. 3, 4, and 5 are fragmentary sections on lines 3-3, 4-4, and 5-5, respectively, of Fig. 2;

Fig. 6 is an end elevation, looking in the direc- 40 tion indicated by the arrows on line 6-6 of Fig. 2;

Figs. 7 and 8 are diagrammatic views illustrating the relationship of one of-the manuals to its associated, heart cam at two extreme positions of the latter; A 45 Fig. 9 which is a view similar to Fig. 1, taken on line 9-9 of Fig. 10, shows .a modified construction in which arms are substituted for cams on the operatin shaftcand Fig. 10 is a fragmentary top plan view of the 50 mechanism shown in Fig. 9. I

The mechanism illustrated in Figs. 1 to 8 comprises a radio chassis frame A in which is mounted a tuning shaft B (with which are associated appropriate condensers or other tuning elements) l and an operating shaft 'C fixed eccentrically in journals M and I5 which are suitably mounted .to rotate in bearings l6 and II, respectively. The latter of these bearings may be carried by a closure plate l8 afllxed over a large opening in one. end of "the chassis frame; when this plate is removed, insertion and removal of the tuning mechanism, as a unit, may be accomplished with ease.

A key-way I9 extends lengthwise of the shaft which at one end isserrated as at 20 to facilitate a driving connection with the journal l5 whereto o it'is fitted.

Upon the shaft are affixed a plurality of elements, each adapted to be driven in response-to operation of a manual, as hereinafter explained. -As shown in Figs. lto 8, each such element may be in the form of a heart cam D made up desirably of two similar complementary plates 2| and 22 in adjacent relation. Both cam plates are apertured to receive the shaft, and at a short distance therefrom are pivotally connected as by means of a boss 23 extruded from one face of each plate to produce'upon its opposite face a corresponding recess 24. By facing two adjacent cam plates in the same direction, the boss of one will enter the recess of the other to provide a pivotal con- .26 nection therebetween. The plates of each cam are provided with registering slots 25 located on the shaft side opposite their pivotal interconnection and at a distance from the shaft which is relatively great; and at opposite ends of each slot are aligned lugs 26 over which are fitted the ends of compression springs 21 whose axes are disposed transversely to a line in intersection with the shaft axis and pivotal axis between the cam plates. With the spring set in place, a tension is'thereby exerted against the two plates of the cam; causing them to engage tightly with the operating shaft so as to be frictionally locked against rotation with respect thereto.

On each side of each pair of cam plates I may place a friction washer 28 (see Fig. 4) having a tongue 29'which extends into the key-way so as to lock the washer with the shaft at all times. Spacers 30 :may also be placed between each of these sets of. friction washers.

At one. end of the operating shaft is secured a washer dl to lock the shaft to the journal l5. To theopposite end of the shaft is afiixed a drum 32 concentric with the journal 14 which is formed. withia hub 33 through which the shaft extends. Beyond this'hub is located a pair of relatively rotatable complementary cam disks 34 and 35 which [are mounted on the operating shaft; these cam disks may be secured on the shaft as by means of a nut 36 and lock washer 31 having atongue disposed within the shaft key-way and an car 38 engaging the nut to prevent rotation thereof after it is once adjustably secured in place. The coacting cam disks are formed on their facing sides with complementary beveled surfaces 39, and one of these disks is provided with a tongue extending into the key-way to lock therewith, the other disk being free to rotate upon the shaft. When the high and low portions of the beveled surfaces on the two cam disks coincide, there is an absence of pressure endwise on the shaft, but by turning one of these disks relative to the other and endwise pressure is exerted along the shaft through the hub 33, the journal I4, the washers 28 and the spacers 30, to lock the several pairs of cam plates fixedly to the shaft in any selected rotative position thereupon. With the cam disks manipulated to relax pressure lengthwise of the shaft, ready adjustment of each heart cam separately will be facilitated.

The range of movement of the operating shaft, say 180, may be fixed as by an arm 4| secured to the journal l which engages at either end of the shaft oscillation with a finger 42 which may be conveniently struck out from the closure plate I 8. The arm 4| is also formed with opposed extensions 43 (Figs. 2 and 3) adapted to be connected as by screws 44 to the ends of a flexible driving disk 45 which is suitably connected to one end of the tuning shaft.

The journal I4 is prevented from turning about the shaft as by a washer 46 (partly shown in Fig. 5) which is similar to a second washer 41. This latter washer is formed with an inwardly extending lug 48 which passes through a slot in the end of the drum hub 33 and into the shaft key-way l9, thereby locking the hub to the shaft. The washer 46 has a similar inwardly extending lug which locks the journal l4 to the shaft. A spring 49 (Fig. 5) serves to press the washers 46 and 41 apart so as to prevent any backlash.

Each of the friction washers 28 is provided with a pair of shoulders 50 and 5| spaced apart something more than 180 (Figs. 1 and 4), each adapted to engage in turn an car 52 which is outwardly struck from one of the cam plates 2| and 22 whereby to limit the adjustment of the heart cams to 180 or thereabouts. The heart cams may be actuated in each instance by'a follower roller 55 which is mounted to move through a fixed path in response to operation of a manual E. In the drawings each manual is represented as a lever 56 hingedly mounted upon a fulcrum rod 51, the manual being normally maintained away from the cam as by a spring 58. Buttons 59, marked with the call letters of the station to which it corresponds, may be ailixed to the outer ends of these manuals which are extended through slots 60 in the front wall of the chassis frame. To operate, the manual corresponding to the station desired is depressed thereby causing the follower roller to turn its associated heart cam to rotate the operating shaft; this movement continues until the roller has advanced as far as possible toward the shaft which position is reached when the roller lies in the notch opposite the point of the heart cam. By so proceeding, accurate tuning may be performed provided that the cam itself has been pre-set properly on the operating shaft.

The drum 32 may be driven by a cord 6! which is wound around a shaft 62 to which is connected a suitable knob, not shown. The drum carries a sheave 63 (Fig. 2) about which passes a cord 64 passing over suitable pulleys 65-, 66, 61 and 68 to connect with an indicator 69 which moves across a scale to indicate the position of the tuning condenser. This scale may be graduated in any suitable units, or it may carry the names of the stations to which the set may be tuned.

The method of adjusting one of the heart cams for a given station may be as follows: The operator first manipulates the coacting cam disks 34 and 35 so as to relax the pressure endwise of the operating shaft. The set is then very accurately tuned by hand into resonance with a desired station. The heart cam representing this station may be adjusted by pressing the manual as far as it will go, the operating shaft meantime being held from rotation. This is easy of accomplishment because, when the cam disks are released, there is no endwise pressure exerted upon the several cams and they are accordingly free, in response to a rotative force suflicient to overcome their frictional engagement with the shaft, to take up new adjusted positions thereupon. Pressure upon one of the manuals may suffice to com- 'plete for the associated cam this adjustment which thereupon becomes very exact and accurate. The remaining heart cams, however, need not be disturbed since each retains its frictional locking engagement with the operating shaft. Each heart cam may, in turn, be adjusted in the same way. With these adjustments made, the cam disks are turned back to locking position whereby all of the heart cams are subjected to endwise pressure and thereby firmly locked once more to the operating shaft.

In Figs. 9 and is shown a modification in which condensers 16 are mounted on a tuning shaft F to which is aflixed a worm wheel 1| meshing with a worm 12, the latter being carried fast on an operating shaft G which is rotatably supported in bearings 13 (one only being shown) mounted on the chassis frame H. The operating shaft to the inside of each bearing is offset slightly, as at 14, this portion of the shaft being adapted to receive a plurality of driven elements I, here shown as arms, each having a roller rotatably mounted thereon. These several arms are held fast between friction washers 16 with intervening spacers 11, as already described in connection with Fig. 2. Means similar to that previously described may be used for providing or releasing an endwise thrust along the operating shaft so as to permit each of the arms to be adjusted rotatively upon the shaft for purposes and in the manner which has been previously described in connection with the heart-shaped cams.

A series of manuals, here shown as levers J, one for each of the arm rollers, are mounted for movement upon a longitudinal rod 80 with spacers 8| intervening to fix the manuals apart a desired distance. Each of these manuals extends over the operating shaft where it is formed with a slot 82 within which the shaft and proximate spacer may lie when the manual is depressed. At the entrance to this slot are opposed bearing points 83 and 84 spaced apart a distance slightly less than the diameter of the arm roller with which these points are adapted to coact. For convenience, each manual is equipped at its outer end with a button 85 on which may be displayed the call letters of a desired station to which the parts associated with this lever may be adjusted. By applying pressure to one of these buttons, the associated lever is moved to swing to its lowest position the roller on the proximate arm thereby rotating the operating and tuning shafts to the exact point required for placing of the condensers in resonance with the station selected. These several manuals may be permitted to ride up and down on the rollers, or each may be held up by a separate spring if so desired.

According to Figs. 1 and 2, the operating shaft is mounted eccentrically in journals which, when rotated, cause the shaft axis to move through an are instead of remaining fixed in accordance with usual practice. The same result follows in the construction of Figs. 9 and 10 wherein the shaft which is offset intermediately of its ends is rotated eccentrically in consequence. The effect in both cases is the same, viz., the centers of the cams or arms with which the manuals coact, when in extreme positions, lie upon opposite sides of the shaft axis which shifts laterally as indicated best in Figs. '7 and 8. In the extreme position of Fig. '1, the manual engages the cam at a point which is off-center with respect to its axis. An initial mechanical advantage is thereby obtained which reduces the effort necessary for starting rotation of the shaft.

I claim:

1. In apparatus of the class described, a chassis, a shaft journaled in the chassis and offset between the journals to provide an elongated eccentric, and a plurality of manually driven elements removably mounted on the shaft.

2. In apparatus of the class described, a tuning mechanism comprising a shaft, driven elements mountedon the shaft, driving manuals arranged to engage the driven elements for turning the shaft to a predetermined tuning position, bearings for the shaft, and journals supportingthe shaft, the latter being offset from the axis of the journals to provide an elongated eccentric whereby to cause the eccentric to describe an are when the shaft is oscillated.

'3. In an apparatus of the class described, a tuning mechanism comprising ashaft, driven elements mounted on the shaft, driving manuals arranged to engage the driven elements for turning the shaft to a predetermined tuning position, bearings for the shaft, journals fixed to the shaft for rotation within the bearings, said shaft being offset between the journals to provide an elongated eccentric whereby to cause the eccentric to describe an are when the shaft is oscillated.

4. In apparatus of the class described, a tuning mechanism comprising a shaft, driven elements mounted on the shaft, driving manuals arranged to engage the driven elements for turning the shaft to a predetermined tuning position, bearings for the shaft, and offset extensions at the shaft ends mounted for rotation within the bearings, said journals and shaft forming an elongated eccentric arranged to describe an are when the shaft is oscillated.

5. In apparatus of the class described, a tuning mechanism comprising a shaft, driven elements mounted on. the shaft, driving manuals arranged to engage the driven elements for turning the shaft to a predetermined tuning position, and a bearingaiournal assembly offsetting the shaft from the axis of the assembly to form an elongated eccentric whereby upon oscillation of the shaft the eccentric is caused to describe an arc.-

ALBERT S. WELLS. II 

